Onyx
Onyx is a white and black banded variety of agate {which is a banded variety of chalcedony (a form of quartz)}. Onyx with white and reddish brown bands is known as sardonyx. Onyx was popular with the ancient Greeks and Romans and remains in high demand today. Pure black onyx is the most common and perhaps the most famous variety.
Onyx is mined in many locations around the world including Brazil, Uruguay and the United States.
